This invention relates generally to electrotherapeutic apparatus, and more particularly concerns improvements in apparatus to generate, control and transmit pulses of high frequency electromagnetic radiation, for application to a patient by means of a treatment head. Such improvements are related to prior apparatus of the type described in prior Kendall and Yarger U.S. Patents.
Prior circuits to generate control and transmit such pulses suffered certain disadvantages. For example, the duty cycles of the pulses, and as defined herein, were relatively low so that the effectiveness and efficiency of the treatment was less than desirable. Also, diamond-shaped or saw-toothed pulses as exemplified in U.S. Pat. No. 3,566,877 to Smith, as well as pulses produced by other devices, contained insufficient pulse energy. Further, the power amplifier stages of prior devices could not adequately handle changes in load current induced by changes in coupling of the treatment head to body loads. Further, harmonics and spurious signals were produced at the input to the power stage, causing difficulty in maintaining good regulation and the required 27.12 megacycle frequency at the head.